In general, the following electric stapler is well known. Sheet staples composed of a large number of linear staples, which are connected with each other being formed into a sheet-shape, are accommodated in a staple cartridge. This staple cartridge is mounted in a passage, which is formed in a magazine portion of the stapler body, used for attaching the cartridge. After the staple cartridge has been inserted and mounted, a staple at the lead of the sheet staples is stricken out while both sides of the staple are being bent, and the following staples are successively stricken out while both sides of the staples are being bent. In this type electric stapler, when a quantity of residual sheet staples in the staple cartridge are decreased, it is necessary to pick up the cartridge from the magazine portion and replace it with a new cartridge. Therefore, it is necessary to provide a staple detecting sensor for detecting the quantity of residual sheet staples in the staple cartridge.
However, a space of the passage provided in the stapler body, to which the staple cartridge is attached, is small. Therefore, even when a common microswitch is attached into the space, a stroke of the switch is too short. Accordingly, the microswitch is operated even when the staple cartridge is moved a little. For example, even when a sufficiently large quantity of staples are left in the cartridge, when the sheet staples are deformed being badly warped, the actuator of the microswitch comes into action. Therefore, the reliability of detection is unavoidably deteriorated. In the case where the microswitch is arranged in the passage, when the actuator is arranged making a right angle with the passage, it obstructs the attaching and detaching work of the staple cartridge. Accordingly, it is necessary to provide a mechanism to prevent the actuator from protruding into the passage in the case of inserting the staple cartridge, which increases the difficulties of arranging the microswitch in the staple cartridge attaching passage. Further, when the sensor is arranged at a position close to the introducing port of the staple cartridge, at the time of inserting the staple cartridge, the staple cartridge is inclined with respect to the passage. Therefore, when the cartridge is attached or detached, the staple cartridge is hooked at the actuator, which causes damage to both the staple cartridge and the actuator. In order to solve this problem, it is necessary to provide a big margin of relief of the actuator.
As described above, it is very difficult to arrange the common microswitch in the stapler body having only a small space.